JP2018051921A - Antistatic polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film having an antistatic layer which is excellent in antistatic properties and uniformity without having stripe-like defects or projections.SOLUTION: There is provided an antistatic polyester film having an antistatic layer on at least one surface of a polyester film, wherein the antistatic layer contains a polymer (A) having an ionic functional group, a nonionic surfactant (B) and an ionic liquid (C) and the content of the ionic liquid (C) is 11 to 35 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an antistatic polyester film having an antistatic layer on at least one side.

  Polyester films are excellent in mechanical properties, heat resistance and transparency, and are widely used as base films and process films for food packaging applications, packaging materials, information storage materials, building materials, electronic materials, printing materials and the like.

Generally, plastic films and their laminated films are prone to static electricity due to contact friction and peeling during processing and when using products, and dust and small dust are likely to adhere due to the influence of the generated static electricity. It is required to have antistatic properties.
As a method for imparting antistatic performance to a film, for example, a method of forming a layer having antistatic performance on a film by a coating film is known.
Patent Document 1 discloses a laminated film containing a polymer containing a carboxyl group and a quaternary ammonium group in an antistatic layer. Patent Document 2 discloses a laminated film containing a urethane resin and an ionic liquid in a surface coating layer.

International Publication No. 2015/152193 Japanese Patent Laying-Open No. 2015-77786

  However, the coating solution for forming an antistatic layer used in Patent Document 1 requires a complicated treatment to obtain a specific dispersed state, and it is difficult to maintain the dispersed state for a long time. In addition, the appearance may change due to agglomeration with the passage of time, and the coating stability may be lowered, and the formed antistatic layer may have streak-like defects or protrusions. Further, in the method described in Patent Document 2, the antistatic property cannot be exhibited unless the film thickness of the surface coating layer to be formed is increased, and the antistatic property is insufficient when the film thickness is small.

  An object of the present invention is to provide a polyester film having an antistatic layer which is excellent in antistatic properties and has no streak-like defects or protrusions and excellent in uniformity.

The inventors of the present invention have arrived at the present invention as a result of repeated studies to solve the above problems.
That is, the gist of the present invention is as follows.

(1) A film having an antistatic layer on at least one side of a polyester film, wherein the antistatic layer has a polymer (A) having a ionic functional group, a nonionic surfactant (B), and an ionic liquid (C) And the content of the ionic liquid (C) is from 11 to 35% by mass.
(2) The antistatic polyester film according to (1), wherein the cation of the ionic liquid (C) is aliphatic quaternary ammonium and / or pyridinium.
(3) Ratio of mass part of polymer (A) having ionic functional group in antistatic layer to total mass part of nonionic surfactant (B) and ionic liquid (C) (A / (B + C) ) Is 55/45 to 85/15, the antistatic polyester film according to (1) or (2).
(4) The antistatic polyester film according to any one of (1) to (3), wherein the average number of streaky defects in the antistatic layer is 1 or less per 1 m of the film width direction.
(5) The antistatic polyester according to any one of (1) to (4), wherein the average number of protrusions having a height exceeding 3 μm in the antistatic layer is 1 or less per JIS A4 size the film.
(6) The antistatic polyester film according to any one of (1) to (5), wherein the surface specific resistance value at 23 ° C. and 50% RH is less than 1 × 10 ¹¹ Ω / □.

According to the present invention, streaky defects and protrusions of the antistatic layer are reduced, and an antistatic polyester film having a more excellent appearance can be provided.
Since the antistatic polyester film of the present invention is excellent in uniformity of the antistatic layer and antistatic performance, it can be used for information storage materials, building materials, printing materials, electronic materials and the like.

The antistatic polyester film of the present invention is a film having an antistatic layer on at least one side of the polyester film.
In the present invention, the polyester resin constituting the polyester film is not particularly limited, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, and a balance between versatility, economic aspect, and mechanical properties. From this point, polyethylene terephthalate is preferable. The polyester resin may be copolymerized with other components as necessary.

Examples of other components copolymerizable with the polyester resin include a carboxylic acid component, a hydroxycarboxylic acid component, and an alcohol component.
Examples of the carboxylic acid component include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid , Maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, cyclohexanedicarboxylic acid, trimellitic acid, trimesic acid, and pyromellitic acid.
Examples of the hydroxycarboxylic acid component include 4-hydroxybenzoic acid, ε-caprolactone, and lactic acid.
Examples of the alcohol component include ethylene glycol, diethylene glycol, 1,3-propanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and bisphenol. Examples include ethylene oxide adducts of A and bisphenol S, trimethylolpropane, glycerin, and pentaerythritol. Two or more of these copolymer components may be used in combination.

  The polyester resin preferably has a melting point of 230 ° C. or higher from the viewpoint of heat resistance.

Examples of the method for polymerizing the polyester resin include known production methods such as a direct esterification method and a transesterification method.
Examples of the direct esterification method include a method in which a necessary monomer raw material is injected into a reaction vessel, an esterification reaction is performed, and then a polycondensation reaction is performed. In the esterification reaction, the reaction is performed by heating and melting at a temperature of 160 ° C. or higher for 4 hours or longer in a nitrogen atmosphere. At that time, oxides such as magnesium, manganese, zinc, calcium, lithium, titanium, and acetate may be used as the catalyst. In the polycondensation reaction, the polycondensation reaction proceeds under a reduced pressure of 130 Pa or less until a desired molecular weight is reached at a temperature of 220 to 280 ° C. At that time, an oxide such as antimony, titanium, germanium, or acetate may be used as a catalyst.
When the polyester resin is polymerized, an antioxidant, a heat stabilizer, an ultraviolet absorber, an antistatic agent, or the like may be added as necessary. Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of the heat stabilizer include phosphorus compounds. Examples of the ultraviolet absorber include benzophenone compounds and benzotriazole compounds.

  The polyester film constituting the antistatic polyester film of the present invention may be an unstretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film. The biaxially stretched film may be either a film obtained by the simultaneous biaxial stretching method or a film obtained by the sequential biaxial stretching method. The polyester film can be appropriately selected and used according to the required properties and according to the properties of the coating liquid used for forming the antistatic layer.

Next, although the manufacturing method of a polyester film is demonstrated concretely, the manufacturing method of a polyester film is not limited to these methods.
The unstretched film is supplied to the extruder with a sufficiently dried polyester resin, melted at a temperature higher than the fluidity, and passed through a filter as necessary. From the T die, the glass transition point of the polyester resin (Tg) It can be obtained by extruding onto a cooling drum whose temperature is adjusted below.

In the uniaxial stretching method, an unstretched film is stretched at a stretch ratio of about 2 to 6 times in the width direction (TD) or the longitudinal direction (MD) in the temperature range of Tg to (Tg + 50 ° C.) of the polyester resin.
In the simultaneous biaxial stretching method, the unstretched film is stretched in the temperature range of Tg to (Tg + 50 ° C.) of the polyester resin in the width direction (TD) and the longitudinal direction (MD) at a stretching ratio of about 2 to 4 times, respectively. Axial stretching. In this case, preliminary longitudinal stretching of about 1 to 1.2 times may be performed before guiding to the simultaneous biaxial stretching machine.
In the sequential biaxial stretching method, the unstretched film is heated with a roll, infrared rays or the like, and stretched in the longitudinal direction (MD) to obtain a longitudinally stretched film. Longitudinal stretching preferably uses a difference in peripheral speed of two or more rolls, and is a stretch ratio of 2.5 to 4.0 times in a temperature range of Tg to (Tg + 40 ° C.) of the polyester resin. The obtained longitudinally stretched film is further subjected to lateral stretching, heat setting, and thermal relaxation in order to obtain a biaxially stretched film. The transverse stretching starts in the temperature range of Tg to (Tg + 40 ° C.) of the polyester resin, and the maximum temperature is preferably in the temperature range of the melting point (Tm) −100 ° C. to (Tm−40 ° C.) of the polyester resin. The transverse stretching ratio is adjusted depending on the required physical properties of the final film, but is preferably 3.5 times or more, more preferably 3.8 times or more, and 4.0 times or more. More preferably it is. After stretching in the longitudinal direction (MD) and the width direction (TD), the film is further stretched in the longitudinal direction (MD) and / or the width direction (TD), thereby increasing the elastic modulus of the film and increasing the dimensional stability. be able to. Following stretching, heat setting treatment for several seconds in the temperature range of Tm-50 ° C to (Tm-10 ° C) of the polyester resin, and relaxation of 1-10% in the film width direction (TD) simultaneously with the heat setting treatment Is preferred.

  The thickness of the polyester film is not particularly limited, and is preferably 12 to 250 μm, more preferably 16 to 150 μm, and still more preferably 20 to 75 μm.

  The polyester film may contain a lubricant as long as the effects of the present invention are not hindered. In addition, the polyester film may be subjected to corona treatment on one side or both sides in order to improve adhesion with a coating solution for forming an antistatic layer.

  The antistatic polyester film of the present invention needs to have an antistatic layer on at least one side of the polyester film, and may have an antistatic layer on both sides. The antistatic layer needs to contain a polymer (A) having an ionic functional group, a nonionic surfactant (B), and an ionic liquid (C).

The polymer (A) having an ionic functional group constituting the antistatic layer may be a polymer (ion conducting polymer) having electrostatic polarization relaxation properties. Examples of the ionic functional group include a quaternary ammonium group, a pyridinium group, a phosphonium group, a sulfonium group, a carboxyl group, a sulfonic acid group, a hexafluorophosphoric acid group, a tetraalkylboric acid group, and a thiocyanate group. The ionic functional group in the combined body (A) can impart quick electrostatic polarization relaxation due to electrostatic polarizability and ionic conductivity.
Especially, it is preferable that the polymer (A) which has an ionic functional group is a polyacryl copolymer which has a quaternary ammonium group in a side chain and also has a carboxyl group in a side chain. The polyacrylic copolymer has significantly improved properties such as adhesion, durability, and heat resistance due to the crosslinking reaction with the crosslinking agent, and the antistatic effect that is effective for polyester film due to the electrostatic polarization relaxation performance of the polymer. Sex can be imparted.
As a specific example of the monomer for constituting a polyacrylic copolymer having a quaternary ammonium group in the side chain and also having a carboxyl group in the side chain, a monomer having a quaternary ammonium group is Examples thereof include dimethylaminoethyl (meth) acrylate quaternized compounds whose ions are methyl sulfate or ethyl sulfate, monomers having a carboxyl group include (meth) acrylic acid, and other monomers ( (Meth) acrylic acid ester, styrene, and other vinyl derivatives.
The composition ratio of these monomers can be selected within a wide range, but the monomer having a quaternary ammonium group should be 15 to 50 mol% with respect to the total monomers of the copolymer. Preferably, the monomer having a carboxyl group is preferably 2 to 15 mol%, and the other monomer is preferably 35 to 83 mol%. When the copolymerization amount of the monomer having a quaternary ammonium group or the monomer having a carboxyl group exceeds this range, the resulting coating liquid containing the polymer (A) has an increased viscosity, resulting in a polyester film. The coatability to the surface may deteriorate.

When the counter ion of the quaternary ammonium group is an alkyl sulfate ion, the quaternary ammonium salt is hardly decomposed by Hoffman by heat, can impart heat resistance to the polymer (A), and maintain antistatic performance. be able to. Specifically, the antistatic layer containing the polymer (A) formed on the polyester film is hardly deteriorated even when subjected to hot press processing at a high temperature for sealing, and maintains heat resistance. Even when heated at 200 ° C. for 1 minute, the increase in surface resistivity is small and antistatic performance can be maintained.
Alkyl sulfate ions, like chlorine ions, are not decomposed and chlorine gas is generated, so that there is no adverse effect such as corrosion of the metal contacting the antistatic polyester film. For example, a trimethylaminoethyl acrylate / chloride copolymer having a chlorine ion as a counter ion decomposes in 1 to 2 minutes when heated to 150 ° C. to generate chlorine gas, and the antistatic performance deteriorates.

  In the present invention, the antistatic layer needs to contain not only the polymer (A) having an ionic functional group but also a nonionic surfactant (B) and an ionic liquid (C). By containing the nonionic surfactant (B) and the ionic liquid (C), it is possible to obtain a high-quality antistatic layer excellent in uniformity without streak-like defects or protrusions.

The antistatic layer is formed by coating a polyester film with a coating liquid containing a polymer (A) having an ionic functional group, a nonionic surfactant (B), and an ionic liquid (C).
The polymer (A) having an ionic functional group constituting the antistatic layer has electrostatic polarization relaxation properties, and further contains a nonionic surfactant (B) and an ionic liquid (C). The antistatic performance of the polymer (A) having an ionic functional group can be brought out to a higher degree.

The nonionic surfactant (B) is preferably a low molecular ion conductive type surfactant in that it can stabilize the antistatic property without depending on humidity, and specifically, Examples include ethylene glycol, acetylene glycol, vinyl alcohol, and alkylglycoside. From the viewpoints of mixing stability in the coating liquid, coating suitability, adhesion, and blocking resistance, acetylene glycol A surfactant is preferred.
The content of the nonionic surfactant (B) in the antistatic layer is preferably 4 to 30% by mass and more preferably 4 to 25% by mass from the viewpoint of antistatic properties and mixing stability. More preferably, it is 4-15 mass%. When the content of the nonionic surfactant (B) is less than 4% by mass, the content effect is small, and projections due to aggregated particles and streak-like defects are likely to occur. In addition, it may not be possible to bring out antistatic performance. On the other hand, when the content of the nonionic surfactant (B) exceeds 30% by mass, the mixing stability in the coating liquid is lowered and the coating liquid tends to be separated.

  The content of the ionic liquid (C) in the antistatic layer needs to be 11 to 35% by mass, and 11 to 25% by mass for the reason that the compatibility, the coating suitability, and the antistatic property become better. It is preferable that When the content of the ionic liquid (C) is less than 11% by mass, the particles of the polymer (A) having an ionic functional group are secondarily agglomerated, causing streaky defects in the antistatic layer, or in some cases agglomerated. May become a problem and may cause problems such as inability to coat. On the other hand, when the content of the ionic liquid (C) exceeds 35% by mass, the adhesion of the coating film is lowered, and blocking tends to occur.

  The ionic liquid (C) is a stable salt having a boiling point of 100 ° C. or lower and a boiling point of 300 ° C. or higher, and at least one of the cation and the anion constituting the ionic liquid (C) is an organic ion. By freely combining cations and anions, physical properties such as melting point and solubility in various solvents can be adjusted, and it has flame retardancy or incombustibility, non-volatility, high thermal stability, and high ionic conductivity.

  Examples of the cation constituting the ionic liquid (C) include pyridinium cation, aliphatic ammonium cation, aromatic ammonium cation, pyrrolidinium cation, phosphonium cation, imidazolium cation, pyrazolium cation, piperidinium cation, and morpholine. A cation, a pyrrole cation, a sulfonium cation, etc. are mentioned. Among these, a pyridinium cation and an aliphatic ammonium cation are preferable because of a good balance of mixing stability, coating suitability, transparency, and antistatic properties in the coating solution, and aliphatic quaternary quaternary. More preferred is an ammonium cation.

On the other hand, examples of the anion constituting the ionic liquid (C) include halide ions (I ⁻ , Cl ⁻ , Br ⁻ etc.), SCN ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , SbF ₆ ⁻ , ^{_{(CF 3 SO 2) 2 N}} -, (CF 3 CF 2 SO 2) 2 N -, Ph 4 B -, (C 2 H 4 O 2) 2 B -, (CF 3 SO 2) 3 C -, CF ₃ COO ⁻ , CF ₃ SO ₃ ⁻ , C ₆ F ₅ SO ₃ ^{— and the} like.

  As an ionic liquid (C), the organic salt compound etc. which consist of a combination of the cation and anion which were illustrated above are mentioned, for example. The method for synthesizing the ionic liquid (C) is not particularly limited, and various organic salt compounds composed of combinations of the cation and the anion exemplified above can be synthesized by a conventionally known method.

  From the viewpoint of ease of handling, the ionic liquid (C) is preferably diluted with a water-soluble organic solvent such as water or ethanol. Examples of commercially available ionic liquids (C) include ELEXEL AS-110 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., EMI manufactured by Kaken Sangyo Co., Ltd., AS300 manufactured by Nippon Emulsifier Co., Ltd., and CIL manufactured by Kaken Sangyo Co., Ltd.

  In the antistatic layer containing the polymer (A) having the ionic functional group, the nonionic surfactant (B) and the ionic liquid (C), the mass part of the polymer (A) having the ionic functional group; The ratio (A / (B + C)) to the total mass part of the nonionic surfactant (B) and the ionic liquid (C) is a viewpoint that the balance between the coating film appearance after coating and the improvement of the antistatic property is good. Therefore, it is preferably 55/45 to 85/15, and more preferably 60/40 to 80/20. When the total content of the nonionic surfactant (B) and the ionic liquid (C) in the antistatic layer exceeds 45% by mass, the formed coating film becomes brittle, and the coating film surface is easily destroyed. Tend to decrease. On the other hand, if the total content of (B) and (C) is less than 15% by mass, it is difficult to maintain the dispersion state of the coating liquid for a long time, and the coating appearance changes due to aggregation over time. The process stability may be lowered, and the formed antistatic layer tends to have streaks and protrusions.

The antistatic layer in this invention may contain a crosslinking agent (D), and the antistatic layer can improve adhesiveness with a base material by containing a crosslinking agent.
Examples of the crosslinking agent (D) include an epoxy compound, a melamine resin, an isocyanate compound, a silane coupling agent, polyethyleneimine, and polyvinyl alcohol, and among them, an epoxy compound and polyethyleneimine are preferable. Two or more types of crosslinking agents (D) may be used in combination.

  In the present invention, a medium such as a polymer (A) having a ionic functional group, a nonionic surfactant (B), an ionic liquid (C) and water is used as a coating liquid for forming the antistatic layer. What was mixed and uniformly dispersed can be used. A coating liquid may contain well-known additives, such as an antifoamer other than the said crosslinking agent (D).

  Examples of the method for producing the antistatic polyester film of the present invention include a method of forming an antistatic layer by applying a coating solution for forming an antistatic layer to the polyester film and drying by heating.

Any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film may be sufficient as the polyester film which coats a coating liquid. Since the drying and curing reaction of the coating liquid can be advanced simultaneously with the stretching and heat setting treatment, when the polyester film is produced by simultaneous biaxial stretching, it is preferable to coat the unstretched film, and sequentially biaxially. When manufacturing by extending | stretching, it is preferable to apply to the uniaxially stretched film after longitudinal stretching, and it is preferable to provide the step of preliminary drying before extending | stretching after coating as needed.
A general coating method can be applied to the application of the coating liquid to the polyester film, for example, Mayer bar coat, air knife coat, reverse roll coat, reverse gravure roll coat, gravure roll coat, lip coat. And a method such as die coating. As for the coating amount of a coating liquid, 1-10 g / m < ² > is preferable. As drying conditions after coating, the drying temperature is preferably 50 to 90 ° C., and the drying time is preferably 10 to 60 seconds. When the film is stretched after coating and drying, the stretching temperature is preferably 110 to 130 ° C., and the stretched surface magnification is preferably 3 to 10 times. Furthermore, when heat-processing after extending | stretching, it is preferable that the heat processing temperature is 220-240 degreeC, and it is preferable that heat processing time is 5 to 15 second.

  In the antistatic polyester film of the present invention, streaky defects and protrusions of the antistatic layer are reduced, and the average number of streaky defects in the antistatic layer is 1 or less per 1 m of the film width direction. It is preferable that it is 0.6 or less. In addition, the average value of the number of protrusions having a height exceeding 3 μm in the antistatic layer is preferably 1 or less and more preferably 0.7 or less per JIS A4 size.

The antistatic polyester film of the present invention preferably has a surface resistivity of less than 1 × 10 ¹¹ Ω / □, and less than 1.0 × 10 ¹⁰ Ω / □ at 23 ° C. and 50% relative humidity. More preferably, it is more preferably less than 5.0 × 10 ⁹ Ω / □. When the surface resistivity of the antistatic polyester film is 1 × 10 ¹¹ Ω / □ or more, the antistatic performance may be insufficient.
From the viewpoint of antistatic performance, the antistatic layer constituting the antistatic polyester film of the present invention preferably has a thickness of 0.05 to 0.5 μm. When the thickness of the antistatic layer is less than 0.05 μm, the antistatic performance may not be exhibited. When the thickness exceeds 0.5 μm, the antistatic performance is saturated.

  The antistatic polyester film of the present invention is excellent in antistatic properties, has reduced streak-like defects and protrusions in the antistatic layer, and has excellent uniformity in the antistatic layer. Therefore, it can be suitably used as an antistatic polyester film in the fields of electrical and electronic parts, optical applications requiring high appearance, design fields, and the like. Taking advantage of such characteristics, the antistatic polyester film of the present invention can be suitably used as a material for various other packaging and industrial applications, and can also be used as a surface film such as a protective film.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

1. Measurement Method (1) Appearance Evaluation of Antistatic Layer (Evaluation Method A)
A sample was prepared so that the longitudinal direction (MD) of the antistatic polyester film was 11 m. At a point 1 m from one end in the longitudinal direction of the sample, a point 1 m from the other end, and a total of 10 points divided by 9 between the two points, a straight line was drawn with a black oil-based pen in the width direction (TD) of the film, respectively. I pulled it.
20 cm from the film to be observed using a high-intensity LED flashlight (M7R type, 400 lumen manufactured by Redlenser) from an angle of about 10 to 45 ° with respect to the surface of the antistatic layer of the antistatic polyester film. By irradiating light from this point, the number of streak-like defects intersecting the straight line was counted over the entire width of the film, the number of streak-like defects per 1 m of film width was calculated, and the average value at 10 points was obtained. .
(Evaluation method B)
Measurement samples (JIS A4 size) were collected from a total of three locations, a central location in the width direction of the antistatic polyester film and two locations 1500 mm in the width direction from that location, and a laser microscope (OLS-4100 made by Olympus) The surface of the antistatic layer was observed at a magnification of 100, the height of the formed protrusions was measured, the number of protrusions exceeding 3 μm was counted, and the average value of three samples was obtained.

(2) Surface resistivity The antistatic polyester film was conditioned at 23 ° C. and 50% RH for 3 hours, and then at the same temperature and humidity, a high resistance meter (Dia Instruments HT-260 type) was used. Then, the surface resistivity value (Ω / □) after an applied voltage of 500 V for 10 seconds was measured at five points, and the average value was obtained.

The following were used as raw materials for preparing the coating solution.
(1) Aqueous dispersion of polymer (A) having ionic functional group / Aqueous dispersion of polymer (A-1): Quaternary ammonium ion-containing acrylic resin (BONDEIP-PA100 manufactured by Konishi Co., Ltd., solid content concentration) 30% by mass)
-Aqueous dispersion of polymer (A-2): cationic acrylic resin (Saftomer ST-3800, manufactured by Mitsubishi Chemical Corporation, solid content concentration: 35% by mass)
-Aqueous dispersion of polymer (A-3): quaternary ammonium ion-containing acrylic copolymer resin (ASA-197 manufactured by Takamatsu Yushi Co., Ltd., solid content concentration 25% by mass)
-Aqueous dispersion of polymer (A-4): Boron ion-containing acrylic urethane resin (Biomicel UB-104 manufactured by Boron Laboratory, solid content concentration: 30% by mass)
-Aqueous dispersion of polymer (A-5): Urethane resin (DIC Corporation Pandex GW-3250, solid content concentration 70 mass%, no ionic functional group)

(2) Nonionic surfactant (B)
Surfactant (B-1): Acetylene glycol surfactant (Olfin E1004 manufactured by Nissin Chemical Industry Co., Ltd.)
Surfactant (B-2): Acetylene glycol surfactant (Surfinol 440 manufactured by Air Products)

(3) Ionic liquid (C) diluent / ionic liquid (C-1) diluent: imidazolium cation-containing ionic liquid (Elexel AS-110 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., dilution solvent: ethanol, concentration 30% by mass)
-Ionic liquid (C-2) diluted solution: alicyclic ammonium cation-containing ionic liquid (EMI, manufactured by Kaken Sangyo Co., Ltd., diluted solvent: ethanol, concentration 30% by mass)
-Ionic liquid (C-3) dilution liquid: Aliphatic quaternary ammonium cation-containing ionic liquid (AS300 manufactured by Nippon Emulsifier Co., dilution solvent: water, concentration 30% by mass)
-Ionic liquid (C-4) diluted solution: pyridinium cation-containing ionic liquid (CIL manufactured by Kaken Sangyo Co., Ltd., diluted solvent: water, concentration 30% by mass)

(4) Crosslinking agent (D)
Crosslinking agent (D-1): Polyethyleneimine aqueous solution (P-1000 manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 30% by mass)
-Crosslinking agent (D-2): Epoxy compound (CR-5L manufactured by DIC, polyhydroxyalkane polyglycidyl ether, solid content concentration: 100% by mass)

Example 1
(Preparation of coating solution)
A nonionic surfactant (B-2) and an ionic liquid (C-4) diluent are added to an aqueous dispersion of the polymer (A-1) having an ionic functional group, and the polymer (A-1): It added so that mass ratio of surfactant (B-2): ionic liquid (C-4) might be set to 78:10:12, and it stirred for 60 minutes. Next, the mixture was diluted with water to adjust the total concentration to 13.0% by mass, stirred for another 30 minutes, stopped and degassed.

(Production of film and formation of antistatic layer)
Polyethylene terephthalate containing 0.08% by mass of amorphous silica particles with an average particle size of 2.3 μm is melt-extruded at 280 ° C., closely adhered to the casting drum by the T-die method-electrostatic pinning method, and unstretched with a thickness of 600 μm. A film was formed. Subsequently, the unstretched film was stretched 3.5 times with a longitudinal stretching roll heated to 90 ° C.
On one side of this longitudinally stretched film, a reverse clavia coater was used to apply the previously prepared coating solution for 1 hour after preparation to a coating amount of 5 g / m ² (WET conversion). Then, the film was stretched 4.5 times at 120 ° C. using a transverse stretching tenter, then heat-treated at 230 ° C. for 10 seconds, cooled, and wound up.
The obtained antistatic polyester film had a thickness of 38 μm, and the antistatic layer had a thickness of 0.15 μm. For this film, the appearance and surface resistivity of the antistatic layer were evaluated. The results are shown in Table 1.
Moreover, it replaced with the coating liquid which passed 1 hour after preparation, applied using the coating liquid which passed 10 hours after preparation, and similarly obtained the antistatic polyester film, Evaluation was performed.

Examples 2-12, Comparative Examples 1-12
Except having changed the kind and compounding ratio of the polymer (A) which has an ionic functional group, a nonionic surfactant (B), and an ionic liquid (C) as shown in Table 1, it carried out similarly to Example 1. Thus, a coating solution and an antistatic polyester film were obtained. When ionic liquids (C-1) and (C-2) are used, ethanol is used as a diluent solvent, and ionic liquids (C-3) and (C-4) are used. When (C) was not used, the dilution solvent was changed to water, and the total concentration of the coating liquid was adjusted to 13.0% by mass, respectively.

Examples 13-15
Except that the types and blending ratios of the polymer (A) having a ionic functional group, the nonionic surfactant (B), the ionic liquid (C) and the crosslinking agent (D) are changed as shown in Table 1. In the same manner as in Example 1, a coating solution and an antistatic polyester film were obtained.

Comparative Example 13
The type and blending ratio of the polymer (A) having an ionic functional group, the nonionic surfactant (B) and the crosslinking agent (D) were changed as shown in Table 1, and an ultrasonic disperser (manufactured by SMT Co., Ltd., The antistatic polyester film was prepared in the same manner as in Example 1 except that UH-600SR-1 type) was used and an ultrasonic dispersion treatment was performed so that the residence time was 5 minutes at 20 kHz. Got.

  Table 1 shows various performance evaluation results of the antistatic polyester film obtained by coating the prepared coating solution.

In Examples 1 to 15, since the antistatic layer contains the polymer (A) having an ionic functional group, the nonionic surfactant (B), and the ionic liquid (C), the coating for forming the antistatic layer is used. Even when the working fluid is left standing for a long time, the number of streaks in the appearance evaluation (evaluation method A) by irradiating a high-intensity LED flashlight and the appearance evaluation (evaluation method B) using a laser microscope The number of protrusions and the appearance was small, and the antistatic performance was excellent.
In Comparative Examples 1 to 4, since the antistatic layer did not contain the nonionic surfactant (B), when the coating liquid for forming the antistatic layer was left standing and applied for a long time, streak-like defects, Protrusions occurred and the appearance evaluation was poor.
In Comparative Examples 5 to 6, since the antistatic layer did not contain the polymer (A) having a ionic functional group and the nonionic surfactant (B), many streak defects existed and the appearance evaluation was inferior. Also, the antistatic property was inferior.
In Comparative Examples 7 to 10, since the ionic liquid (C) was not contained in the antistatic layer, there were many streak-like defects, and when the coating liquid for forming the antistatic layer was applied after standing for a long time, A protrusion was generated in the prevention layer, and the appearance evaluation was poor.
In Comparative Example 11, since the content of the ionic liquid (C) formed in the antistatic layer did not satisfy the range specified in the present invention, there were many streak-like defects in the antistatic layer and the appearance evaluation was inferior. It was.
In Comparative Example 12, since the antistatic layer did not contain the polymer (A) having an ionic functional group and the content of the ionic liquid (C) did not satisfy the range specified in the present invention, the antistatic property It was inferior to.
In Comparative Example 13, an antistatic layer having a good appearance with few streak-like defects and protrusions was obtained when the coating liquid subjected to ultrasonic dispersion treatment was prepared and coated 1 hour later. However, the antistatic layer obtained from the coating solution 10 hours after the preparation had streaky defects and protrusions, and was poor in appearance evaluation.

Claims (6)

  A film having an antistatic layer on at least one side of a polyester film, wherein the antistatic layer contains a polymer (A) having an ionic functional group, a nonionic surfactant (B) and an ionic liquid (C). An antistatic polyester film, wherein the content of the ionic liquid (C) is 11 to 35% by mass.   The antistatic polyester film according to claim 1, wherein the cation of the ionic liquid (C) is aliphatic quaternary ammonium and / or pyridinium.   The ratio (A / (B + C)) of the mass part of the polymer (A) having an ionic functional group in the antistatic layer and the total mass part of the nonionic surfactant (B) and the ionic liquid (C) is The antistatic polyester film according to claim 1 or 2, which is 55/45 to 85/15.   The antistatic polyester film according to any one of claims 1 to 3, wherein an average value of the number of streaky defects in the antistatic layer is 1 or less per 1 m of the film width direction.   The antistatic polyester film according to any one of claims 1 to 4, wherein an average value of the number of protrusions having a height exceeding 3 µm in the antistatic layer is 1 or less per JIS A4 size. The antistatic polyester film according to any one of claims 1 to 5, wherein a surface specific resistance value at 23 ° C and 50% RH is less than 1 × 10 ¹¹ Ω / □.